Will contact tracing be key in stopping the spread of the coronavirus?

Will contact tracing be key in stopping the spread of the coronavirus?

If you were like many of us on the Kojo team, you watched the movie “Contagion” when the coronavirus began to spread — and quickly realized how eerily similar it is to what’s going on today. Will the movie itself save us? No. But what the doctors and scientists did in the movie just might.

When the “Contagion” virus starts spreading, contact tracers try to find where it originated. According to the Centers for Disease Control: “In contact tracing, public health staff work with a patient to help them recall everyone with whom they have had close contact during the timeframe while they may have been infectious. Public health staff then warn these exposed individuals (contacts) of their potential exposure as rapidly and sensitively as possible.”

Contact tracing is being done all across the country, including in Arlington County. But is it being done on a large enough scale to make a difference? And how can your smartphone help with contact tracing? 

Produced by Kurt Gardinier


  • Mary-Anne Liles Public Health Nurse, Arlington County Department of Human Services; @ArlingtonDHS
  • Lei Zhang Director, Maryland Transportation Institute; @MarylandTransp1


  • 12:00:04

    KOJO NNAMDIYou're tuned in to "The Kojo Nnamdi Show" on WAMU 88.5. I'm broadcasting from home, so, welcome. Later in the broadcast, we're cooking up the latest installment of Kojo for Kids with “MasterChef Junior” Che Spiotta. But first, if you are like many of us on the Kojo Show team, you watched the movie "Contagion" when the coronavirus began to spread. And if you did it, you quickly realized how eerily similar it is to what's going on today, especially with what the doctors and scientists did in the movie in terms of contact tracing, which is now being done all across the country, including in Arlington County. But is it being done on a scale large enough to make a difference? We'd like to hear from you. Any questions about contact tracing? Give us a call. Joining us now is Mary-Anne Liles. She is a Registered Public Health Nurse with the Arlington County Department of Human Services who's now working with the county's COVID-19 investigations team. Mary-Anne Liles, thank you for joining us.

  • 12:01:04

    MARY-ANNE LILESWell, thanks for having me, Kojo.

  • 12:01:06

    NNAMDIFirst, what is contact tracing?

  • 12:01:10

    LILESYou know, contact tracing, the purpose of it is to quickly identify persons diagnosed with a communicable disease, and the persons that they may have exposed to prevent further infection among additional people.

  • 12:01:24

    NNAMDIOkay. You're notified that Jane Doe tests positive for the virus. Then what? Walk us through the steps that you and your colleagues follow from that point onwards.

  • 12:01:35

    LILESSure. So, the Health Department does receive all the individuals in Arlington that test positive. They're given to us, and we attempt, as quick as possible, to go ahead and reach out and contact that individual. You know, it is a little bit different. With every phone call that we have, we gather the information, make sure we have the right phone number, and we go ahead and contact them. As soon as we get them on the phone, we ask them how they're feeling. We want to check in with them. And at that point when we know that they're okay, they're all right to go ahead and give us an interview, then we start collecting data. It's their symptoms, how they're feeling, when the first onset of that symptom was is very important, because we like to trace their contacts 48 hours prior to the onset of symptoms. And, as we go through that, collecting the data, collecting the contacts, at that point we finish up.

  • 12:02:38

    LILESWe've gotten as much information as we can, and we hand that over to another part of our contact tracing team, which is risk assessment and active monitoring.

  • 12:02:47

    NNAMDIWhat's the basis for the 48-hour period that you use by their contacts that they've seen 48 hours before the onset of symptoms? What if they're not showing symptoms when they test positive, and they don't show symptoms for another week? It's still 48 hours?

  • 12:03:05

    LILESSo, that makes a good point, because I know that we're doing antibody tests and other things, as well. But the 48 hours is when we're assuming that they are infectious. When they're out and about, that is the time that they could transmit the disease. If they are asymptomatic, and we do have some of that, then that's a different process that we go through when we're talking about quarantining. We still will ask them to quarantine, and it usually will be the same amount of time from the date that they had the test, or looking at that 48 hours as well.

  • 12:03:41

    NNAMDIMary-Anne Liles, who's getting the virus in Arlington County, and how are they typically infected?

  • 12:03:45

    LILESYou know, when we first started doing this, I will say that back in mid-March, we were receiving positive cases from every zip code in Arlington. About four or five weeks ago, we definitely saw an uptick in the concentration, were certain zip codes and mainly essential workers. And that's been very hard for us.

  • 12:04:12

    NNAMDIWhen you say essential workers, who are you talking about? Are you talking about healthcare professionals or all essential workers?

  • 12:04:21

    LILESI'm talking about all essential workers. Healthcare workers, for sure, and not just people that are in the hospital, but people that are also in assisted care living. They're caretakers of other individuals in nursing homes or even independent living. I'm talking about construction workers. I'm talking about landscapers, people that work in the grocery store, food handlers.

  • 12:04:45

    NNAMDIWe're talking with Mary-Anne Liles. She's a Registered Public Health Nurse with the Arlington County Department of Human Services. She's now working with the county's COVID-19 investigations team. We're talking with her about contract tracing. Mary-Anne, how willing are people to give you the names of all of the people they've been in contact with after they've test positive?

  • 12:05:04

    LILESYou know, Kojo, that's a great question. At first, people were pretty readily giving us the information that we needed to do effective contact tracing. We have noticed over recent weeks, when we call -- and you've got to understand, the calls that we make, they vary. So, we may call an individual. They answer the phone. They've been able to quarantine themselves. They have resources to be able to stay home and do that. They have healthcare. But, again, sometimes a call may led us to somebody that is in the hospital. They're unable to give us the information that they need. And we will try and get that, either some of it from a nurse or a family member. And then the third type of calls, which is probably the most right now, the ones we're talking about, the essential workers. When we do call, you will hear some chaos in the background, sometimes kids talking, adult conversations, and you're realizing right pretty quickly that there's probably not a lot of room for quarantine and isolation.

  • 12:05:04

    LILESAnd when we start asking for those household contacts, those people that are living in that home with them, people have become very guarded. It's very unfortunate. We do our best. We tell them that the Public Health Department is here to help them, that it not only is good for them, but it's good for others, and how important it is to actually stop the transmission of the disease.

  • 12:05:04

    LILESBut, of course, if those people are in precarious situations, or precarious immigration situations themselves, if they happen to be undocumented, I guess, in some cases, one can understand their reluctance to share information about others who might be in a similar situation.

  • 12:05:04

    LILESI would agree. And that's exactly what we're running into. Not every case, but there is that element that's occurring. The best we can do, I think that in Arlington County, you know, we have a great message out there. We're there for everybody. We are all in this together. Our health and well-being is dependent on every individual. And we'll try to let them know how much we value them. They are actually the ones out there working for us, so we can stay home. And yet they're the ones that are the sickest. They're the ones that don't have easy access to healthcare or testing. And now we're asking people that are already vulnerable to stay home and lose the wages. And so there's a lot of resources. There's a lot of things that we're trying to do to help this population.

  • 12:05:04

    LILESAnd what if the person you are contacting does not have health insurance or the means to stay home for 14 days?

  • 12:05:04

    LILESWell, that's another good question and another dilemma. Though, I will say, I can't speak for every jurisdiction, but Arlington County has been wonderful in this way. If an individual can't stay home, there are means. There's mechanisms in place -- and I'm not in that section. We're actually on the front end of case investigations. But they will link them -- Arlington County links them to services. It might be rental assistance. It might be financial assistance and food assistance.

  • 12:05:04

    LILESDo you test people who are identified as having been in contact with an infected patient or do you recommend that you seek out testing on their own?

  • 12:05:04

    LILESThat also is done over an active monitoring. Like when we take all the contact's information we do ask the contacts to monitor themselves. We actually call them and make sure they're taking their temperature and they don't have symptoms. And if somebody were to come down with symptoms, then we would recommend that they get tested.

  • 12:05:04

    LILESHere is Linda in Tacoma Park, Maryland. Linda, you're on the air. Go ahead, please.

  • 12:05:04

    LILESThanks. I've been looking for a job as a contact tracer, and I've applied for maybe for five or six jobs, different parts of the country. I haven't gotten any, so I'm wondering if there's any insight as to why it's taking such a long time.

  • 12:05:04

    LILESYou haven't gotten any responses as yet, is what you're saying, Linda?

  • 12:05:04


  • 12:05:04

    LILESI don't know. Do you know, Mary-Anne Liles? What does it take?

  • 12:05:04

    LILESWell, I know here in Arlington County, we have something called MRC, which is a Medical Reserve Corps. We also have a lot of nurses in Arlington County. So, I do work for the Health Department, but I also work in school health. So, prior to this pandemic, we had a lot of nurses in the schools doing case management. We also do a lot of line listing, if there's NOROVIRUS, strep, so we are very familiar with this. Of course, not at this scale. So, for Arlington County, we were able to move into this COVID response pretty smoothly. And the Medical Reserve Corps has provided many volunteers, as well. So, that's what we're doing here, in Arlington County. I do hear, though, that there are a lot of jurisdictions that will be hiring a lot of contact tracers, and I believe the District of Columbia is one of them.

  • 12:05:04

    LILESSo those are the places, Linda, you may be seeking to apply to, and hopefully there will not be a significant delay in helping you to figure out exactly what you need to do. But thank you very much for your call. Mary-Anne, Arlington County is one of the richest counties in the nation. Do you have the resources you need to do your job successfully and help stop the spread of the virus?

  • 12:05:04

    LILESWell, at the moment, I think Arlington County is doing a great job. I'm not on the finance side, so I don't know so much about that. But I will tell you that not only have we been able to beef up the contact tracing -- we have I think approximately 250 people at the moment doing it, which is so important -- but we also have a community that is very giving. So, a lot of the individuals staying home, they not be able to help volunteer, but they have given a lot of donations to rental assistance, food assistance and other things, which has helped us a lot.

  • 12:05:04

    LILESHow effective do you think contact tracing is in preventing the spread of the coronavirus?

  • 12:05:04

    LILESYou know, I think it's a tool. People have to adhere to what they're being told about isolation and quarantine. But I think that it is very helpful. And when you think about it, the Arnott factor, I believe, is about three. So, for one individual, they can actually be infectious to three individuals. And if we can effectively shut down or stop even one chain of transmission, that can possibly keep a lot of people from being infected. And I think the other thing -- I ran into something yesterday. I worked a 12-hour shift yesterday. I worked with several people. I was in what they call a team lead position.

  • 12:05:04

    LILESOnly got about 20 seconds left, but go ahead.

  • 12:05:04

    LILESI was looking at all the interviews, and one thing that I did notice in the contact tracing is that several of them all had gone to a certain place, a certain convenience store. So, through the contact tracing, we were able to identify a place in which people gathered.

  • 12:05:04

    LILESGot it.

  • 12:05:04

    LILESAnd be able to recommend what we needed.

  • 12:05:04

    LILESMary-Anne Liles, I'm afraid we're out of time. Thank you for joining us. We got to take a short break. We'll be right back. I'm Kojo Nnamdi.

  • LILESWelcome back. It's hard to enforce social distancing, or to even know if people are actually obeying stay-at-home orders. But researchers at the University of Maryland are keeping score by using something that just about everyone has, your cell phone. Joining us now is Dr. Lei Zhang, a Professor in the Department of Civil and Environmental Engineering at the University of Maryland and Director of the Maryland Transportation Institute. Lei Zhang, thank you for joining us.

  • LILESIt's my pleasure, Kojo.

  • LILESLei Zhang, what is the Interactive Analytics platform?

  • LILESYes. So, if your audience members haven't been there, I would encourage everybody to check out this COVID-19 Impact Analysis platform that researchers at the University of Maryland have put up has a public open access information at data.covid.umd.edu. So, this is where you can find information about how your communities, your counties and states are doing in terms of social distancing, as well as reopening assessment, reopening readiness.

  • LILESHow does this work? How many cell phones are you monitoring, and how are you able to access them?

  • 12:13:56

    LEI ZHANGWell, first of all, I want to make it clear that we are looking at anonymized mobile device location data. So, we do not have any personal information and the data are collected soon are often processed. So, privacy is very well-protected. What we do at the Maryland Transportation Institute is that we use these anonymized and aggregated mobile location data to be able to tell the general public, as well as decision-makers, the percentage of people who are staying at home, the overall distancing behavior, and we only report the results at the county and the state level for the entire nation. And we update this information on a daily basis.

  • 12:14:42

    NNAMDIAs he mentioned, the website is data.covid.umd.edu. How many cell phones are you monitoring?

  • 12:14:52

    ZHANGCorrect. It is data.covid.umd.edu.

  • 12:14:56

    NNAMDIHow many cell phones are you monitoring and how are you able to access them without extracting any personal information?

  • 12:15:02

    ZHANGSo, on a monthly basis, we're looking at a fairly large sample. So, maybe a little bit of background information. So, Maryland Transportation Institute and our CATT Laboratory, you know, we've been running the largest transportation and mobility data center in the nation for the past 20 years. So, we've developed a collaboration with a number of mobile device data aggregators. So, that's how we get access to the anonymized mobile device location data from I would say more than 100 million mobile devices on a monthly basis across the nation. So, that would allow us to produce a fairly accurate anonymized and aggregate level results on social distancing and mobility behavior across the nation.

  • 12:15:48

    NNAMDILei Zhang, you track 16 different criteria that you use to calculate a state's score. Which of those 16 are the most important criteria?

  • 12:15:58

    ZHANGRight. So, on our platform, we not only use mobile device data. We also aggregate data from government agencies and from other researchers to, really, to be able to provide a comprehensive picture of how each state and each county in the nation is prepared for reopening, or for the next phase of more broadly reopening their businesses. You're right. Out of the 38 metrics in four categories we report on our platform, including information on mobility behavior and social distancing, COVID cases in house, economic impact and the vulnerable populations, we selected 16 of them for what we call the Society and Economy Reopening Assessment. So, out of these 16, to answer your question, we look, for instance, the first six variables that are the most important public health variables that all the authorities, like the World Health Organization, the federal government, the CDC all recommend as getting criteria.

  • 12:17:05

    ZHANGSuch as number of days with decreasing COVID case numbers, testing capacity, contact tracing that you and the previous guest were discussing. And it was a lot of information, as well as hospital beds and ICU bed utilization. So, these are the six very critical public health variables. But we also report a number of other variables, such as, you know, number of imported cases, because of travel from outside of our region to District of Columbia, Maryland, as well as, you know, a number of other metrics that the audience members can find on our website.

  • 12:17:43

    NNAMDIHow have D.C., Maryland and Virginia scored throughout all of this?

  • 12:17:48

    ZHANGIn terms of social distancing, our region actually has been doing the best job in the nation, even better than New York City. District of Columbia has always, in our data, been ranked in number one in the nation in terms of social distancing. What that means is that we have the most people actually staying home. Our residents in our region are making fewer trips, and so it's doing all of that social distancing discipline in order to slow down the spread of the virus. So, we're doing really well in D.C., Maryland and Northern Virginia on social distance and morbidity. We're doing relatively well compared to the rest of the nation in terms of our economy. You know, nobody's economy is good. But our economy, right now, is actually better, in relative terms, compared to the rest of the nation. But, in terms of public health variables, we are still, you know, based on our data, our testing capacity in our region still needs improvement.

  • 12:18:53

    ZHANGWe still need contact tracing workers. I heard one of the people who called in earlier is looking for job. I really hope that people like her, who is looking for contact tracing, can actually fill these positions as quickly as possible. So, we still need to do a bit more on improving our testing capacity, number of contact tracing workers, and we still need to wait for a bit longer in terms of wait for that number of cases to actually go down in our region.

  • 12:19:20

    NNAMDISpeaking of contact tracing, in Singapore and South Korea, mobile apps are being used to carry out contact tracing, and there's a push in Europe to carry out contact tracing through cell phones, as well. Is that something that you can see happening here in the U.S.?

  • 12:19:35

    ZHANGU.S. certainly has been debating about this. You have a great observation on what's going on in the rest of the world. In some of the Asian countries, such as, as you mentioned, Singapore, South Korea and China, they've actually really just, you know, been taking everybody's cell phone data to try to do this individual level contact tracing using technology. So, what the technology can do is that it enables a single contact tracing worker to be able to manage contact tracing for more cases on a daily basis. Certainly, there is huge privacy concern about these kind of practices. Then, in Europe, you also observed that they are also looking at using cell phones to do contact tracing as a way to supplement the traditional boots-on-the-ground contact tracing. But, in Europe, such as in U.K. and other countries, they're taking a slightly different approach from some of the Asian countries.

  • 12:20:37

    ZHANGSo, they use an opt-in approach. So, everyone can decide for him or herself whether not he or she is willing to sign up onto one of these mobile contact tracing apps. But the critical factor is that, you know, studies have shown that you need at least 50, 60, maybe even 70 percent of the population to be enrolled in the same contact tracing platform for that technology actually to be effective. Now, in the U.S., are we expecting more than 60 percent of individuals to be willing to sign up voluntarily into a contact tracing location tracking app? My guess is probably not. So, it's interesting to see how, you know, the U.S. will be able to leverage technology with consideration for privacy protection to be able to help us, you know, really fight this pandemic with different kinds of contact tracing techniques.

  • 12:21:39

    ZHANGBut, in the meantime, I think still, you know, the thing we can do immediately is still to hire more contact tracing workers.

  • 12:21:47

    NNAMDIIn the 30 seconds we have left, what has surprised you most about the data you've collected?

  • 12:21:53

    ZHANGWhat has surprised us most was that people really don't like social distancing. In mid-March, you know, we have seen significant increases social distancing. But, after one month of staying home, starting around mid-April, we are seeing that people just made their own minds that they had enough. They don't want to stay at home longer. So, all the metrics are going down. And that is a concern. So, I think we either need to reopen or we need to --

  • 12:22:24

    NNAMDILei Zhang, thank you so much for joining us. We're going to take a short break. When we come back, we'll meet Che Spiotta, the winner of season seven of “MasterChef Junior.” I'm Kojo Nnamdi.

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